Onboarding is unclear for people. So if they just Google Lemmy it's a bit of a adventure for them to figure out they have to make an account where to make the account.

The friction around account creation is difficult. Many let me instances require manual approval, so that slows down me onboarding funnel.

Let's be Frank most people don't want to make an account, entering email and password and validation. Using some federated identity like Google Apple would make The onboarding easier for people

Discovery is very difficult, especially if you're on a smaller instance, you have to know what communities to individually subscribe to. There's some mitigations with find a Lemmy community websites but they're not built into most of the apps yet. So unless you're joining a very large server, Lemmy's going to feel pretty empty.

There's some gaps between Lemmy and other platforms around media rich posts, especially videos and GIFs. Posting a video on Lemmy is difficult especially if you're on a mobile device.

I still love Lemmy, these are just observations with respect to your query